Objectives Test if animal movement can change the outcome of ecological interactions in a grassland ecosystem
Refine PIT tag methodologies for use in other systems.

Progress and Results Streams matter to a grasslands ecosystem. Ecosystem function and functioning ecosystems within these streams also matter. Multicellular animals, especially motile organisms, affect ecosystem function and functioning ecosystems. Specifically, motile organsims (a) can affect productivity as vectors for nutrient and energy transport, (b) provide unique pathway for upstream (multidirectional) flux of nutrients and energy, (c) their biodiversity can add stability to ecosystems. In particular, crayfish may play an important role in stream ecosystem function because they play a central role in aquatic and riparian food webs and act as an energy and nutrient transport vehicles in several food webs. Specifically, they connect autotrophic (algae, macrophytes) and heterotrophic (detrital) production with higher terrestrial (raccoon, birds) and aquatic (fish, otters) trophic levels. They are also very abundant and occur throughout a stream ecosystem. In the summer of 2012, we externally PIT tagged 181 crayfish. In one pool, four stationary PIT tag antenna were sited. Across multiple pools, we conducted a mobile pit tag survey. 137 of 181 tagged crayfish were detected at least once in 5 weekly backpack surveys. About 75% of these were detected by stationary antenna. By examining distribution patterns and relating them to environmental correlates, we are using these data to test how movement defines interactions, the role of abiotic escape, the impact of biogeochemical hotspots and how niche partitioning affects crayfish distributional patterns. These methods and results have generality to a wide range of fish and ecosystems including fish in Great Plains streams and rivers.